1. Field of Inventions
The present inventions relate generally to implantable infusion devices.
2. Description of the Related Art
Implantable infusion devices have been used to provide patients with a medication or other substance (collectively “infusible substance”) and frequently include a reservoir and a pump. The reservoir is used to store the infusible substance and, in some instances, implantable infusion devices are provided with a refill port that allows the reservoir to be transcutaneously filled (and/or re-filled) with a hypodermic needle. The reservoir is coupled to the pump, which is in turn connected to an outlet port. A catheter, which has an outlet at the target body region, may be connected to the outlet port. As such, infusible substance from the reservoir may be transferred from the reservoir to the target body region by way of the pump and catheter.
Implantable infusion devices may also include a side port that facilitates access to the outlet port and catheter. The side port, which is typically accessed by way of a hypodermic needle, allows the clinician to push fluid into the catheter or draw fluid from the catheter to check for catheter occlusion, sample cerebrospinal fluid (CSF), inject contrast dye into the patient and/or catheter for use during a fluoroscopic procedure, remove medication from the catheter prior to dye injection, inject additional medication into the target region at the catheter outlet and/or remove pharmaceuticals or other fluids that are causing an allergic or otherwise undesirable biologic reaction. The side port is frequently located at the outer perimeter of the infusion device in order to increase the likelihood that the side port will be tactilely distinguished from the refill port.
Accessing the side port with a hypodermic needle can, however, be difficult. For example, the outer perimeter location of the side port can make access difficult and, in those instances where the patient is obese, it can be difficult to tactilely distinguish the side port from the refill port. As a result, clinicians may incorrectly determine that the refill port has been accessed, when in fact the side port has been accessed, and vice versa. Such incorrect access determinations can lead to refill medication being delivered to the side port instead of the refill port and/or contrast dye being delivered to the refill port instead of the side port. Incorrect access determinations can also lead to medication and contrast dye being delivered to the wrong location within the patient's body when no port is accessed, e.g. to pump pocket instead of to the region near the catheter outlet. Incorrect side port access determinations can also result in an unfounded catheter patency verification. In the exemplary context of medication delivery to the intrathecal space, the clinician may draw a clear fluid (e.g. serous fluid from the abdomen) into a syringe when side port has not been properly accessed. The clear fluid may be mistaken for CSF from the intrathecal space which, in turn, may lead the clinician to determine that a catheter is not blocked without actually having drawn fluid from the catheter.
Accordingly, the present inventors have determined it would be desirable to provide the clinician with confirmation that the side port has been successfully accessed.